With increasing the processing power of servers, a problem occurs in which the electric power consumption of the server is increased. In order to solve this problem, a method for reducing the power consumption of a server system has been proposed.
Japanese Patent Application Laid-Open No. 2007-213167 discloses a method in which the electric power consumption of a whole system including a computer is compared with a predetermined power limit threshold value. When the electric power consumption of the whole system is equal to or greater than the predetermined power limit threshold value, the electric power consumption of the computer is limited based on a power saving policy that indicates the minimum usable electric power of the computer.
Japanese Patent Application Laid-Open No. 2007-310791 (paragraph numbers 0021 and 0032, and FIGS. 1, 6 and 9) discloses a method in which when a predetermined condition is met, for example, a sever is added to or removed from a computing system, and many tasks are imposed upon (integrated to) a server whose electric power consumption per performance is small within a processing capability of the server that is decided by considering a fixed requirement performance that is set to each task in advance. By using this method, a number of the servers upon which no task is imposed can be increased and the electric power consumption can be reduced.
The electric power consumption of the entire system can be restricted to the predetermined value without reducing a number of computers in the system or decreasing CPU performance of each computer by using the method disclosed in Japanese Patent Application Laid-Open No. 2007-213167. The method disclosed in Japanese Patent Application Laid-Open No. 2007-310791 allows to realize the low power consumption of the whole server system.
However, recently, the CPU performance of servers has been further enhanced. Additionally, because a plurality of high-performance CPUs are mounted in one server, the electric power consumption tends to be increased. When a information processing device which CPUs is mounted on densely, such as a blade server is used, a large amount of electric power has to be supplied. Therefore, the amount of electric power supplied to the information processing device further increases. For this reason, a technology has been sought in which the electric power consumption of the whole server system can be reduced has been sought.